Telephone system



June 1, 1937. o. CESAREO TELEPHONE SYS TEM Filed March 15, 1935 lNl/ENTOR O. CESAREO A T TOR/VE V Patented June 1, 1937 UNITED STATES PATENT QFFHCE TELEPHONE SYSTEM poration of New York Application March 13, 1935, Serial No. 10,780

8 Claims.

This invention relates to telephone systems and particularly to telephone line circuits of the coin controlled or prepayment type.

In a copending application Serial No. 10,779,

filed March 13, 1935, there is disclosed a telephone system of the coin controlled type in which means is provided for removing the marginal condition formerly imposed on the coin collector magnets which results in an increase in the loop range 10 over which coin collection is permissible. This arrangement, however, is applicable only to systems which do not require preliminary coin tests to be made, such as automatic telephone systems in which other means are provided for guarding against the fraudulent use of the telephone equipment.

It is the object of this invention to provide a telephone system of the coin controlled type in which the marginal condition heretofore imposed on the coin collector magnet is reduced and the loop range over which coin collection is permissible is increased and in which provision is made for permitting the usual coin tests to be made. I

This object is attained in accordance with a feature of the invention by associating with a telephone subscribers line of the coin controlled type, a combined gas-filled tube and rectifier unit which functions to perform the marginal and polar requirements heretofore carried out by the coin collector magnet and which permits the regular coin tests to be made.

The invention will be readily understood from the following detailed description made with ref- 5 erence to the accompanying drawing which shows a subscribers line circuit of the coin controlled type terminating at a central office at a manual operatcrs switchboard position and equipped with a two-coil coin disposal magnet,

40 one of said coils being connected to the subscribers line circuit by way of a rectifier and the other of said coils being connected to the line circuit by way of a gas-filled tube and the answering end of an operators cord circuit equipped with 45 the necessary instrumentalities for making coin tests and for effecting the collect and refund operations of the coin disposal equipment at the subscribers station and having associated therewith battery 33 which supplies current for talk- 50 ing purposes.

A subscriber at station 2, desiring to initiate a call, removes the receiver .from its switchhook at the calling station and deposits a coin or token C in the coin receptacle located at the station in 55 accordance with regular practice. A circuit is thereupon established which may be traced from grounded battery, winding of line relay 3, inner armature and back contact of cut-off relay 4, tip conductor of the calling line, through the subscribers line loop, now closed at the receiver 5 switchhook contacts, ring conductor of the calling line toground by Way of the back contact and outer armature of relay 4. Relay 3 operates in this circuit and at its armature and front contact completes an obvious circuit for line lamp 10 5 which is associated with jack 6 at which the calling subscribers line terminates.

Upon noting the lighted line lamp 5, an operator inserts plug 1 of one of her cord circuits such as D, into jack 6 of the calling line. A cirl5 cuit is thereupon established which extends from grounded battery, filament of lamp 8, sleeve contacts of plug l and jack 6, winding of cut-off relay 4 to ground. Lamp 8 is lighted in this circuit and relay 4 operates, the latter opening the ener- 20 gizing circuit for line relay 3 which thereupon restores its armature to normal, extinguishing the line lamp 5.

The operator may then connect her head set (not shown) with the cord D in the well known 5 manner, inquire of the calling subscriber the number of the line with which a connection is desired and proceed to make the required coin tests.

The coin test is made by applying a low voltage 30 negative test to the calling line and following it with a low voltage positive test. In order to simplify the disclosure, applicant has elected to show a test key T for this purpose which is manually operated by the operator twice, first to the left 35 and then to the right. It is to be understood that this test may be performed in any other suitable manner, as for example, by means of an operators key which need be actuated but once to set in operation equipment which functions automatically to apply the double voltage tests in the proper sequence.

In the system disclosed, the operator actuates the key T to the left which causes the continuity of the cord circuit to be interrupted and a circuit including the winding of relay ii to be established. This circuit extends from the low voltage negative battery ll, winding of relay 9, upper left spring and alternate contact of key T, normal back contacts and tip springs of keys C and R, tip contacts of plug 1 and jack 6, tip conductor of the calling line, conductor it to the point l2. At this point there are two paths which, under suitable conditions, may be completed to ground at the coin contacts I3, one by way of the rectifier l4, collector magnet coil l5 and conductor l6 and the other by way of the gas-filled tube I l, winding of relay l8, collector magnet coil I9 and conductor 16.

Though the polarity of battery I l as applied to the cathode 20 of tube I! is negative, the tube I! will not function because it is designed to break down only at a voltage of approximately sixty volts which is considerably in excess of the voltage of battery 5 I. I2 to ground at the coin contacts I3 by way of the tube ll accordingly remains open.

The rectifier I 4 is so poled as to oppose the flow of current from the negative battery ll, so that the branch circuit from point [2 to the coin contacts I3 is also not completed at this time and relay 9 does not operate. However, should the calling subscriber, in an endeavor to fraudulently use the telephone, simulate the coin ground by grounding the line circuit, such a ground would have to be applied ahead of the rectifier or gas tube since such equipment including the coin disposal mechanism is enclosed and not accessible. In this event the relay 9 would operate and bring in the lamp signal 20 to advise the operator that the line circuit was either accidentally or fraudulently grounded.

After actuating key T to the left, the operator actuates it to the right to put the relay 2 l which is connected to the low voltage positive battery 22, in operative association with the coin disposal mechanism at station 2. A circuit is now established extending from the positive terminal of battery 22, winding of relay 2 I, right-hand alternate contact and tip spring of key T, left-hand normal contact and tip spring of key T, normal contacts and tip springs of keys C and R, tip contacts of plug 1 and jack 6, tip conductor of the calling line, conductor Ii) to the point l2 where the circuit divides, as previously described. The polarity of battery 22 and the potential thereof are such as to preclude the possibility of tube I! operating. The polarity is such however, as to allow the current to pass through the rectifier M and thence to ground by way of the magnet coil 15, conductor l6 and coin contacts i3. This current is not sufficiently great to cause the effective energization of coil 45 but is of sufficient magnitude to cause sensitive relay 2| to operate and establish an obvious circuit for lamp signal 23. The lighting of lamp 23 indicates to the operator the presence of a coin in the coin receptacle at station 2. Should lamp 23 fail to light upon the operation of key T to its right-hand position the operator would know that the calling subscriber had failed to deposit a coin in the coin receptacle.

From the foregoing it is apparent that the rectifier and gas-filled tube combination of this invention functions to provide a positive anti-beat coin test.

Assuming now that the connection desired by the calling subscriber has been extended by the operator and the calling and called parties have completed their conversation and replaced their receivers on their respective switchhooks, the operator, being advised in the well known manner that the call has been terminated, would then actuate key C in her cord circuit, to cause the coin disposal mechanism at station 2 to function to collect the coins deposited by the calling subscriber.

The closure of key C completes a circuit extending from the positive terminal of coin collect battery 25, alternate contact and tip spring of key C, normal contact and tip spring of key R, tip

The branch circuit from point contacts of plug 1 and jack 6, tip conductor of the calling subscribers line, conductor l0, rectifier l4, magnet coil 15, conductor [6 to ground at the coin contacts l3. The coil [5 is fully energized in this circuit and causes the collector to operate and collect the deposited coins. It will be noted that the positive potential of battery 25 is also impressed on the cathode of tube H but does not cause the break down of the tube due to the fact that the tube is polarized and functions only on the application of a negative polarity thereto. After the restoration of key C, the connection may be taken down by the operator whereupon all actuated apparatus is restored to normal.

Should the operator be unable to extend the connection to the called subscriber, or should the calling subscriber abandon the call before the called subscriber answers, the operator would be so advised and would actuate the key R to cause the coin disposal magnet to function to refund the coins deposited by the calling subscriber. The actuation of key R causes a circuit to be established which extends from the negative terminal of refund battery 28, alternate contact and tip spring of key R, tip contacts of plug 1 and jack 6, tip conductor of the calling line, conductor [8 to the cathode 26 of tube ll. Cathode 29 of the tube ll is grounded at the coin contacts I 3 by Way of resistance 30, winding of sensitive relay l8, coil 89 and conductor 15. The potential of battery 28 is sufiiciently great and of correct polarity to cause the tube 5'! to break down and complete the circuit therethrough. The tube gap between cathodes 2i) and 29 breaks down first and causes an initial ionization of the gas contained in the tube, whereupon the tube anode is brought into circuit and the ionization is maintained by Way of the cathode 20 and the tube anode. Relay l8 operates as a consequence of the flashing of tube 61 and establishes a locking circuit foritself to the tip side of the line circuit independent of the tube ll, the tube i? now being short-circuited. The short circuiting of the tube ll decreases the resistance of the established circuit to such a value as to permit the coil l9 to be sufiiciently energized to cause the coin magnet to operate and refund the coins deposited by the calling subscriber.

The arrangement described herein presents an extremely high resistance to ground for transmission purposes as the tube ll presents an open circuit to ground at low central office potentials and the rectifier presents a high resistance to pulsating voice currents superimposed on negative battery. It provides a substantially positive anti-beat coin control circuit and, by permitting the use of a single coil to ope-rate the coin magnet, extends the possible loop range by approximately 1000 ohms or double the resistance value of a single magnet coil.

What is claimed is:

1. In a telephone system, a telephone line having a station thereon, a coin disposal mechanism at said station, a coil for eifecting the actuation of said mechanism in one manner, a coil for effecting the actuation of said mechanism in another manner, means actuated upon the deposit of a coin in said mechanism for preparing a circuit for each of said coils, a test circuit including a low potential negative battery, a test circuit including a low potential positive battery, means included in series with one of said coils and said line for permitting the flow of current from one of said batteries and resisting the flow of current from the other of said batteries, and means for connecting said test circuits to said line.

2. In a telephone system, a telephone line having a station thereon, a coin disposal mechanism at said station, a coil for effecting the actuation of said mechanism in one manner, a coil for efiecting the actuation of said mechanism in another manner, means actuated upon the deposit of a coin in said mechanism for preparing a circuit,

for each of said coils, a test circuit including a low potential negative battery, a test circuit including a low potential positive battery, means included in series with one of said coils and said line for resisting the flow of current from said batteries, means included in series with the other of said coils and said line for permitting the flow of current from one of said batteries and resisting the flow of current from the other of said batteries, and means for connecting said test circuits to said line.

3. In a telephone system, a telephone line having a station thereon, a coin disposal mechanism at said station, a coil for eifecting the actuation of said mechanism in one manner, a coil for effecting the actuation of said mechanism in another manner, means actuated upon the deposit of a coin in said mechanism for preparing a circuit for each of said coils, a negative low potential test battery, a positive low potential test battery, a high potential battery, means included in series with one of said coils and said line for permitting the flow of current from said high potential battery and resisting the flow of current from said low potential batteries, means included in series with the other of said coils for resisting the flow of current from one of said low potential batteries and said high potential battery and permitting the flow of current from said other low potential battery, and means for connecting said batteries to said line.

4. In a telephone system, a telephone line having a station thereon, a coin disposal mechanism at said station, a coil for efiecting the actuation of said mechanism in one manner, a coil for effecting the actuation of said mechanism in another manner, means actuated upon the deposit of a coin in said mechanism for preparing a circuit for each of said coils, a test circuit including a low potential negative battery, a test circuit including a low potential positive battery, an asymmetrical conductor interposed between one of said coils and said line for permitting the flow of cur-- rent from one of said batteries and resisting the flow of current from the other of said batteries, and means for connecting said test circuits to said line.

5. In a telephone system, a telephone line hav-- ing a station thereon, a coin disposal mechanism at said station, a coil for effecting the actuation of said mechanism in one manner, a coil for efiecting the actuation of said mechanism in another manner, means actuated upon the deposit of a coin in said mechanism for preparing a circuit for each of said coils, a test circuit including a low potential negative battery, a test circuit including a low potential positive battery, a gaseous conductor included in series with one of said coils and said line for resisting the flow of current from said batteries, an asymmetric conductor included in series with the other of said coils and said line for permitting the flow of current from one of said batteries and resisting the flow of current from the other of said batteries, and means for connecting said test circuits to said line.

6. In a telephone system, a telephone line having a station thereon, a coin disposal mechanism at said station, a coil for effecting the actuation of said mechanism in one manner, a coil for effecting the actuation of said mechanism in another manner, means actuated upon the deposit of a coin in said mechanism for preparing a circuit for each of said coils, a negative low potential battery, a positive low potential battery, a high potential battery, a gaseous conductor included in series with one of said coils and said line for permitting the flow of current from said high potential battery and resisting the fiow of current from said low potential batteries, an

asymmetrical conductor included in series with the other of said coils for resisting the flow of current from one of said low potential batteries and said high potential battery and permitting the flow of current from said other low potential battery, and means for connecting said batteries to said line.

7. In a teelephone system, a telephone line having a station thereon, a coin disposal mechanism at said station, a coil for effecting the operc ation of said mechanism in one manner, a coil for effecting the operation of said mechanism in another manner, means actuated upon the deposit of a coin in said mechanism for preparing a circuit for each of said coils, a negative low poten- 1 tial battery, a positive low potential battery, a negative high potential battery, a positive high potential battery, a gaseous conductor included in series with one of said coils and said line for permitting the flow of current from said negative high potential battery and resisting the flow of current from said other batteries, an asymmetrical conductor included in series with the other of said coils and said line for resisting the flow of current from said negative high potential battery and said negative low potential battery and permitting the flow of current from positive potential batteries, and means for connecting said batteries to said line.

8. In a telephone system, a telephone line having a station thereon, a coin disposal mechanism at said station, a coil for effecting the operation of said mechanism in one manner, a coil for effecting the operation of said mechanism in another manner, means actuated upon the deposit of a coin in said mechanism for preparing a circuit for each of said coils, a polarized voltage responsive device connected in series with one of said coils and said line, a polarity discriminating device connected in series with the other of said coils and said line, said first device functioning to complete the prepared circuit for said first coil only upon the application of a relatively high negative voltage to said line and said second device conducting current to said second coil only upon the application of positive voltages to said line, and means for applying said voltages to said line.

ORFEO CESAREO. 

